Band-pass filters are well known. Band-pass filters are commonly used in communication systems, where high-frequency signals are down converted and often demodulated into low frequency signals. A well-suited architecture is typically chosen depending on the input bandwidth, adjacent channels, and requested sensitivity and selectivity of the system implementing the band-pass filter.
Most band-pass filters are made from conventional transconductors, which typically include differential pairs of transistors, and these band-pass filters are often tuned with a high-impedance bias voltage. Some other filters are tuned with a low-impedance source. For example, filters using the Nauta transconductor are tuned by changing their supply voltage.
Process variations of transconductors are well-known problems. However, conventional solutions for filters tuned with a low-impedance source have not been implemented to adequately address process variations.
Accordingly, what is needed is a system for providing an improved band-pass filter. The present invention addresses such a need.